Gas scrubber

ABSTRACT

A gas scrubber is provided for the removal of particulates and chemical contaminants from air and other gases. The particulates and chemical contaminants are removed from gas drawn through the scrubber, by inertial separation, spraying with water or liquid chemicals, and filtering techniques. A throat section of adjustable cross-sectional area is provided in the scrubber to provide optimum air velocity and turbulence for maximum scrubbing efficiency over a wide range of air handling capacities. A two stage sump is provided for the spray water or liquor to prevent clogging of the spray nozzles. Removable filter baskets of variable depth are utilized during final treatment of the air or gas being cleaned.

United States Patent 1191 Perez Dec. 24, 1974 GAS SCRUBBER 3,405,91810/1968 Calaceto et al 261/DIG. 54 1151 11119111911 Manuel River vale,3353'??? 3/33; rililr' ii'iiijjiiij 557233 [73] Assignee: AerosolsControl Corporation, O IG PATENTS OR APPLICATIONS Englewood 1,807,80311/1968 Germany 261/62 [22] Filed: Aug. 11, 1972 1,235,414 6/1971 GreatBritain 26l/DIG. 54 [21] Appl' 279848 Primary Examiner-Bernard NoziickAttorney, Agent, or Firm-Robert. A. Maikis [52] US. Cl 55/223, 55/226,55/228,

55/233, 55/259, 55/481, 55/496, 55/518, [57] ABSTRACT 261/DIG- 541 261/118 A gas scrubber is provided for the removal of particu- [51] Int. ClBold 47/06 lanes and chemical Contaminants from air and Othsr [58] heldof Search 55/220 2231 2281 gases. The particulates and chemicalcontaminants are 55/4751 481, 518; removed from gas drawn through thescrubber, by in- 261/DIG- 621 118 ertial separation, spraying with wateror liquid chemi cals, and filtering techniques. A throat section of ad[56] References Clted justable cross-sectional area is provided in thescrub- UNITED STATES PATENTS her to provide optimum air velocity andturbulence 1,358,333 11/1920 Rudloff 55/475 for maXimum Scrubbingefficiency Over a Wide range 1,831,782 11/1931 Strindberg 55/228 x ofair handling capacities. A two stage sump is pro- 2,234,735 3/1941Lambert et a1. 1. 261/D1G. 54 vided for the spray water or liquor toprevent clogging 2,337,983 12/1943 Fisher 261/DIG. 54 of the spraynozzles. Removable filter baskets of vari- 3 1 S g/ZZ; able depth areutilized during final treatment of the air i c amy..... 2,585,440 2/1952Collins 55/228 x or gas bemg cleaned 2,873,816 2/1959 Umbricht et a1261/D1G. 54 8 Claims, 10 Drawing Figures if i/ f! a? A/rnal/fl i/ 1PATENTED DEC 24 I974 sum 1. 95 5 BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates generally to pollution controldevices and more particularly to an improved gas scrubber for removingparticulates and chemical contaminants from air and other gases.

2. Description of the Prior Art Gas scrubbers are employed to removepollutants and other undesirable matter from air or other gases.Protection of the earths environment demands that many different typesof contaminants be removed from air or other gases which are vented tothe atmosphere from incinerators and various industrial processes. Forexample, dust and chemical fumes generated by indus try must be removedto promote community health. Gas scrubbers are also used in manyindustrial pro cesses to recover valuable minerals or other air bornematerials from waste gases so that the recovered materials may bereused. Finally, gas scrubbers are often employed to treat polluted airfrom the atmosphere to provide a source of clean air for homes,buildings and sensitive industrial processes.

The pollutants to be removed from air or other gases compriseparticulates which are essentially solid materials carried along in theair flow. Examples of this type of pollutants are dust from industrialgrinding operations and fly ash from refuse burning. Additionally, theair or gas may contain chemical contaminants such as acid fumes or gaseswhich are produced during chemical processes. Particulates and gaseousor liquid pollutants entrapped in the air are removed in prior art gasscrubbers by a wide variety of techniques. The particulates, forexample, are often removed by inertial separation which results when anair stream moving at a relatively high velocity is suddenly changed indirection to expel the particulates by centrifugal force. Sprays ofwater or various liquid chemicals are injected into the air stream toremove chemical gases and liquid particles carried along in the stream.The sprays effectively wash" the air and eliminate the undesirablechemicals by adsorption or chemical reaction with the liquid beingsprayed. Finally, filters of various materials are employed for removalof various types of pollutants.

The presently known types of gas scrubbers generally are designed andbuilt for specific applications and are constructed for a particularrange of air flows. When the rate of air flow or the volume handled ischanged for a particular scrubber, the scrubber usually must be modifiedto handle the different air flow parameters with maximum cleaning orscrubbing efficiency. Consequently, any change in the process in whichthe gas scrubber is employed may result in costly and timeconsumingmodifications being made to the gas scrubber itself. Additionally, gasscrubbers using water or chemical sprays to wash the gas or air beingtreated are subject to periodic shut downs because the nozzles whichspray the water or liquid chemicals become clogged with the pollutantstrapped in the spray. Filters employed in known gas scrubbers are alsosubject to the requirement of frequent cleaning and other servicing tomaintain a peak operating efficiency for the gas scrubber unit. Finally,it is desirable that all gas scrubbing equipment have low power andwater requirements, be self-contained, mechanically-rugged and be ofcompact size and weight.

SUMMARY OF THE INVENTION It is an object of this invention to provide agas scrubber which is readily adapted for applications having a widerange of gas flow rates and which may be easily modified in the field tosuit a wide range of applications.

It is a further object of this invention to provide a gas scrubberhaving a novel, two-stage sump arrangement which minimizes nozzleclogging and shutdown time.

It is a still further object of this invention to provide a gas scrubberhaving a filter arrangement which pro vides for easy maintenance of thefilter media and for adjustment of the depth of the filter media.

It is another object of this invention to provide a gas scrubber havingno moving parts and which is of mechanically-rugged construction. Y

It is an additional object of this invention to provide a gas scrubberhaving low power and water usage re quirements and which is of compactsize and weight.

Briefly, the gas scrubbing apparatus of the invention comprises ahousing having a gas inlet and a gas outlet. Baffle means in the housingform a passageway connecting the gas inlet with the gas outlet. Thepassage way is provided with an adjustable throat portion having areduced cross-sectional area and spray means are disposed in the throatportion to produce a liquid spray across the throat portion, so that gaspassing through the throat portion from the gas inlet to the gas outletis increased in velocity and turbulence and scrubbed by the liquidspray. In one embodiment of the invention, the throat portion of thepassageway comprises the space between a substantially coplanar movablebaffle and a substantially coplanar fixed baffle. In another embodimentof the invention, one baffle of the said movable and fixed baffles issubstantially coplanar and the other baffle has two portions, each ofwhich is substantially coplanar, which are inclined at an acute anglewith the plane of said one: baffle, so that the cross-sectional area ofthe throat portion formed by the baffles gradually tapers to a minimumat the apex of the two inclined portions of the said other baffle, tothereby provide a smooth transition from the larger cross-sectional areaof the passageway to the smaller cross-sectional area of the throatportion. In still another embodiment of the invention, the housing ofthe gas scrubber is provided with a liquid-filled sump portion and meansare provided for controlling the level of the liquid in the sumpportion. In this embodiment, a fixed baffle is disposed above thesurface of the liquid in the sump portion and the throat portion of thepassageway is formed by the space between the fixed baffle and thesurface of the liquid in the sump portion.

The sump portion of the housing; of the gas scrubber of the inventionmay be divided into two sections or stages" by a filter. One of the sumpsections is disposed beneath the throat area of the passageway in thehousing, so that the heavy particulate matter and contaminants in thegas being scrubbed fall into the said one section of the sump. The othersection of the sump is utilized as the source of liquid for the spraynozzles in the housing, so that the filtered liquid drawn from the saidother section of the sump prevents clogging of the spray nozzles.Additionally, removable filter baskets may be disposed in the passagewayin the housing adjacent the gas outlet of the housing to provide one ormore final treatments for the gas passing through the scrubber.

The nature of the invention and other objects and additional advantagesthereof will be more readily understood by those skilled in the artafter consideration of the following detailed description taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view of a gas scrubber constructed in accordancewith the teachings of the present invention;

FIG. 2 is a full sectional view of the gas scrubber taken along the line2-2 in FIG. 1 of the drawings;

FIG. 3 is a front elevational view of the gas scrubber of FIG. 1 withportions of the service doors broken away to reveal details ofconstruction;

FIG. 4 is a rear elevational view of the gas scrubber shown in FIGS. 1-3of the drawings;

FIG. 5 is a plan view showing the top of the gas scrubber of FIGS. 1-4of the drawings;

FIG. 6 is a perspective view of one of the filter baskets of the gasscrubber of the invention with the sup port rods and top screen removedfor convenience of illustration;

FIG. 7 is a side elevational view, partly in section, of the nozzle andpipe arrangement employed to produce the liquid sprays in the gasscrubber of the invention;

FIG. 8 is a sectional view of the throat portion of the gas scrubber ofthe invention showing an alternative movable baffle construction,

FIG. 9 is a side full sectional view of a gas scrubber constituting analternative embodiment of the invention; and

FIG. 10 is a perspective view of the nozzle and pipe arrangementemployed to irrigate the filter baskets in the embodiment of theinvention shown in FIG. 9 of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Referring nowto FIG. 1 of the drawings, there is shown a gas scrubber constructed inaccordance with the teachings of the present invention. The gas scrubberhas a housing which is provided with an air inlet duct 21. The inletduct 21 is adapted to be connected to a source of polluted or dirty airor other gas. For example, when the combustion products of refuseburning or incineration are to be treated, the inlet duct 21 may bedirectly connected to the flue of the incinerator. The combustionproducts are then passed through the gas scrubber 20 and the clean airis drawn out of an outlet duct 22 located on the top 23 of the gasscrubber. As illustrated in FIG. 1, the outlet duct 22 is connected by aduct 24 to a blower or air handler 25 which serves to physically drawthe air through the gas scrubber from the inlet duct 21. In thepreviously mentioned example, where the inlet duct is connected to theflue of an incinerator, the blower 25 may have its outlet 26 connectedback to the flue for venting to the atmosphere or may be connected to aseparate venting arrangement. Although the gas scrubber of the inventionwill be described with reference to the removal of pollutants from air,it will be understood that it may be employed to remove pollutants orother undesirable contaminants from any gas. Accordingly, the inlet duct21 may, for example, be connected to the waste gas output from achemical process and the outlet 26 of the blower 25 connected to a stackor other venting arrangement for venting to the atmosphere. The housing20 of the gas scrubber and the inlet and outlet ducts should preferablybe constructed of a material which will not chemically react with thepollutants in the air or gas being treated. Accordingly, the housing andthe hereinafter described interior parts of the scrubber may beconstructed, for example, of a 12 gauge mild steel, stainless steel, aglass fiber material or a plastic such as polyvinyl chloride.

The housing 20 has a front panel 27 in which a pair of outwardly openingservice doors 28 and 29 are provided for purposes hereinafter described.As seen in FIGS. 2, 4 and 5 of the drawings, a rear wall 30 is providedwhich does not extend the full height of the unit. Side panels 31 and 32are connected by means such as welding, for example, to the top 23, thefront panel 27 and the rear panel 30 to provide a basic box-likeenclosure. The side panels 31 and 32 are each provided with an extendedportion 33 of approximately the same height as the rear panel 30, towhich the rear panel 30 is connected. A panel 34 to completely enclosethe top of the unit. The side panels 31 and 32 are respectively providedwith flanges or feet 35 and 36 upon which the unit rests. A rectangularfioor 37 is connected by means such as welding, for example, to thefront panel 27, the rear panel 30 and the two side panels 31 and 32 toform a liquid-tight enclosure or sump 38 in the lower portion of thehousing 20. The aforementioned construction provides an opening 39between the rear wall 30 and the panel 34 through which access to thesump 38 may be had. The floor 37 is arranged to slope downwardly towardthe rear panel 30 so that relatively heavy particulate matter or othercontaminants removed from the air during the scrubbing process settle inthe sump and flow downwardly toward the end panel 30. It will be notedin FIG. 2 of the drawings that the panel 34 in the rear of the unit doesnot extend down the full length of the unit to reach the floor 37, sothat a rectangular opening 40 exists through which the sludgeaccumulating in the sump 38 is permitted to flow toward the end panel30. The accumulated sludge may be conveniently removed through thepreviously described opening 39. Reinforcing members 41 are connectedbetween the side panels 31 and 32 underneath the floor 37 to provideadded strength to bear the weight of the liquid in the sump 38.

As seen in FIG. 2 of the drawings, the sump 38 is divided into twosections or stages 42 and 43 by a vertical wall or member 44 which isconnected between the side walls 31 and 32 of the unit. The wall 44 isprovided with an opening 45 at the lower end thereof in which a screenor filter 46 is disposed, so that liquid in the sump is free to passfrom one stage to the other stage but heavy particulate matter or sludgeis prevented from entering the sump section 42. Again, the interior ofthe housing, the wall 44 and the filter 46 are preferably fabricated ofa material which does not chemically react with the liquid in the sumpor the contaminants removed from the air being treated. It will be notedthat the section 42 of the sump is located at a higher elevation thanthe sump section 43 because of the inclined floor 37 of the housing. Thesump section 43 is disposed beneath the portion of the interior of thegas scrubber which first receives the untreated air from inlet duct 21,so that it is this section of the sump which receives the largest amountof heavy particulates and other contaminants. The filter 46 in the wall44 prevents these large particles from entering sump portion 42. Anoutlet pipe 47 is connected to the higher elevation end of sump section42 and communicates with the input of a pump 48 which is located outsideof the housing 20. The pump 48 is driven by an electric motor 49 so thatthe liquid in the sump 38 may be used in the various spray sections ofthe unit which will be described hereinafter, thereby providing a closedor recirculating spray system. The sump 38 is initially filled by freshwater or other liquid from a pipe 50 having a valve 51 located therein.This inlet pipe communicates with the sump section 43 through housingwall 31 and is provided with a float valve 52 and a float 53 so that theliquid in the sump may be maintained at a predetermined level. A surfacedrain pipe or skimmer 54 is located at the low elevation end of sump 38to act as a safety device to prevent overfilling of the sump in case thefloat valve 52 becomes inoperative. The skimmer 54 is connected to anupper pipe section 55 by a threaded connector 56, so that the overallheight of the drain pipe may be altered to control the level of theliquid in the sump. It may be noted that the surface drain arrangementmay also be utilized to skim surface froth or contaminants from thesurface of the liquid in the sump 38.

As seen in FIG. 2 of the drawings, the dirty or untreated air is drawnthrough inlet duct 21 by the action of the blower 25 and is immediatelydeflected in a downward direction by a fixed baffle 57 which isconnected to the top 23 and side wall 31 of the scrubber housing. As theuntreated air passes through inlet duct 21, a nozzle 58 provides aquenching spray which tends to cool the untreated air and thereby reduceits volume for easier handling by the gas scrubber. The spray fromnozzle 58 also tends to agglomerate the particulate matter and othercontaminants in the untreated air into heavy particles which fall intothe sump section 43. The nozzle 58 communicates directly with the outputof the pump 48 by means of pipes 59, 60 61 and 62, so that the liquid inthe sump 38 is pumped directly into the nozzle 58 to produce theagglomeration spray. The liq uid in the sump may be water or maycomprise various liquid chemicals which are used for treating chemicalcontaminants in the dirty air. For example, if the principal pollutantbeing treated is a phenol compound, the sump liquid could comprise aliquid solution of potassium permangenate which is employed to oxidizethe phenol compounds in the air. If the untreated or dirty air containedacid fumes, the sump solution might be a caustic solution which wouldneutralize and remove the acid fumes. Accordingly, the chemicalcomposition of the liquid in the sump which is employed for theagglomeration nozzle 58 is determined by the nature of the pollutantsbeing treated.

After the air passes through the agglomeration spray and is directeddownwardly by the fixed baffle 57, it strikes the surface 63 of theliquid in the sump and then strikes a movable baffle 64, so that is iscompletely reversed in direction and passes through a throat 65 formedby the fixed baffle 57 and the movable baffle 64. This 180 reversal indirection of air flow acts to remove relatively heavy contaminants orparticulate mat ter, such as grinding dust, for example, by inertialsepa ration. Since the particulate matter is heavier than the air andwater droplets, the centrifugal force acting upon these particlesproduces a greater force on the particulate matter which is thendirected downwardly into the sump liquid. The air and any fine orlightweight particles in the air, however, pass upwardly through thethroat 65. It may also be noted that some inertial separation occurswhen the untreated air enters the inlet duct 21 and is deflected 90downwardly by the action of fixed baffle 57. The separated particulatematter in this section would tend to collect on the baffle 57 and iswashed into the sump section 43 by the action of the spray from nozzle58.

The baffle 64 is movable for reasons which will be hereinafter describedand is made of sufficient length so that the lower end 66 thereof iswell below the surface 63 of the liquid in the sump. The top of thebaffle is secured to a bracket 67 which has a bolt 68 passingtherethrough. The bolt 68 passes through a slot 69 formed in the sidewall 31 of the scrubber housing and through an aperture in a cover plate70 disposed on the outside of the housing. A nut 71 is provided on theend of the bolt 68 so that the bracket: 67 may be clamped in place atsome point along the length of the slot 69. The cover plate 70 preventsthe escape of untreated air to the exterior of the scrubber housing. Asimilar bracket and slot arrangement, indicated generally by referencenumeral 72, is provided at a lower point along the length of the movablebaffle 64 which is above the surface 63 of the liquid in the sump, sothat the movable baffle is supported on one side thereof by the housingwall 31. The other side of the movable baffle is supported by a lock bararrangement 73 which is connected between the fixed baffle 57 and abaffle-wall member 74. The lock bar 73 passes through an aperture formedin the movable baffle 64 and the baffle is held in place on the lock barby washers and nuts (not shown) on the rod so that lateral adjustment ofthe baffle may be made. The lock bar arrangement is utilized because aservice door 75, as shown in FIGS. 1 and 5 of the drawings, is providedin the housing side wall 32 to permit the air inlet and throat sectionsof the scrubber to be cleaned and serviced when required. Consequently,the top of the movable baffle 64 which is adjacent the side wall 32 maynot be connected to the side wall by a bracket and slot arrangement. Thelower end of the movable baffle, however, may be connected by a suitablebracket and slot arrangement (not shown) to the side wall 32, so thatthe movable baffle may be laterally adjusted and locked in place at adesired position.

As the air to be treated passes through the throat formed by the fixedbaffle 57 and the movable baffle 64, it passes through a liquid sprayfrom a row of nozzles 76 which are spaced at predetermined points alongthe length of a pipe 77. The pipe 77 is horizontally disposed so that ahorizontal spray is set up across the entire width of the passageway 65.The pipe 77, as seen in FIG. 1 of the drawings, is connected by a teefitting 78 and the pipe 62 to the output side of pump 48 so that theliquid in the sump is forced out through the nozzles 76. It may be notedthat a thin slot or opening may be formed in the pipe 77 running thelength thereof to provide the liquid spray instead of utilizing the rowof nozzles 76. The use of such a slot would essentially provide a solidjet or curtain of liquid running completely across the throat 65 and maybe desirable for some applications.

The adjustable or movable baffle 64 permits the cross-sectional area ofthe throat portion 65 to be adjusted to produce optimum scrubbingconditions. As the cross-sectional area of this portion of thepassageway is gradually narrowed, the velocity of the air passingthrough the passageway is speeded up and a turbulence is created whichgreatly aids the scrubbing action caused by the liquid spray fromnozzles 76. In general, the adjustment of the baffle will depend on therate of flow of the air being treated and the scrubbing efficiencyrequired. As the baffle is moved closer to the fixed baffle 57, theReynolds Number of the flow is in creased and consequently a highturbulence is created which produces a good mixing action between theair being treated and the fine droplets of water or liquid chemicalsforming the spray from nozzles 76. This thorough scrubbing actioneffectively eliminates the fine particulate matter and other chemicalcontaminants which the first stages of the scrubbing process miss.Additionally, since the row of nozzles 76 are aimed substantiallyhorizontally to produce a spray pattern which strikes movable baffle 64,the spray will bounce back and forth several times between the movablebaffle 64 and the fixed baffle 57, so that extremely fine droplets ofthe liquid spray are produced. The high velocity of the air passingthrough the throat 65 effectively produces gas stream atomization, sincethese very fine droplets of liquid are sheared by the high velocity airinto micron-sized droplets. Again, this action materially increases theefficiency of the scrubbing process. In effect, the movable baffle 64permits the throat area 65 to act as a single dimensional Venturi. Thisfeature also allows a single size of gas scrubber to accomodate a widevariation in the flow rate of the air being treated, so that a unit inthe field may be switched over to different processes or uses withoutexpensive and time consuming structural modifications. The disclosedvariable throat arrangement also provides a longer residence time forthe air in the scrubber to thereby promote a more complete and thoroughchemical reaction of the pollutants with the liquid spray. The width ofthe throat portion 65 may vary from about 1 inch to 5 inches, where the5 inch size would be used for a flow rate of about 5,000 CFM. It will beapparent that if the movable baffle 64 is moved too close to the fixedbaffle 57, the velocity of the air will be increased to a very highrate, but at the same time a large pressure drop will be created throughthe throat area which will impose a substantial load on the blower 25.Accordingly, as mentioned previously, the setting of the size of thethroat area will be determined by the parameters of the process or fieldof application for which the scrubber is used.

When the air leaves the throat portion 65 of the passageway, it passesaround the top edge of the movable baffle 64 and strikes the top 23 ofthe scrubber housing. It then strikes fixed baffle or wall member 74 andis directed downwardly through a passageway 79 until it strikes thesurface 63 of the liquid in the sump section 43. By virtue of thisarrangement, the direction of the air flow in the passageway 79 iscompletely reversed from the direction of the air flow in the throat 65,so that another inertial separation is performed thereby removing moreparticulate matter. As the air is reversed in direction at the upperportion of the passageways 65 and 79, it is passed through anothercurtain of spray formed by a row of nozzles which are disposed along thelength of a horizontally extending pipe 81. The pipe 81, as seen in FIG.1 of the drawings, is con nected by means of a tee fitting 82 and pipes60, 61 and 62 to the output side of pump 48 so that the liquid from thesump section 42 is forced through the nozzles 80 to create the spray.This spray agglomerates the fine contaminated water droplets which arethen dropped out in the sump by the inertial forces involved inreversing the direction of air flow. As the air leaves passageway 79, itstrikes the surface 63 of the liquid in sump section 43 and is thendrawn upwardly through a passageway 83 which is formed by the wallmember 74 and the front wall 27 of the scrubber housing. This passagewaycommunicates directly with the gas outlet duct 22. Again, the directionof the air flow in passageway 83 is opposite to the direction of the airflow in passageway 79, so that another inertial separaion of particulatematter is performed. It will be noted that any remaining heavyparticulate matter which accumulates on the walls of passageway 79 iswashed down into sump section 43, so that these large particlesaccumulate with the other sludge material in the sump portion in whichthe float valve 52 is located. Since this sump section is separated bythe screen or filter 46 from the sump section 42, only relatively cleanliquid is passed through the outlet pipe 47 to the input of pump 48. Byvirtue of this arrangement, the heavy particulate matter and othercontaminants are prevented from entering the spray pipes and cloggingthe nozzles in the scrubber, thereby minimizing maintenance andshut-down time.

The passageway 83 is a two stage filtering section which is composed ofa first filter basket 84 and a second filter basket 85. The constructionof each of the filter baskets 84 and 85 is identical and is shown inFIG. 6 of the drawings. As seen in FIG. 6, each filter basket comprisesa substantially rectangular hollow frame 86 which is closed at thebottom by a gas permeable end member 87. The end member 87 should befabricated of screen or mesh material, so that the filter material ormedia is held in place in the basket but gas or air is allowed to passthrough. The filter media (not shown) is packed in the basket formed byframe 86 and bottom 87 and a mesh or screen cover member 88 is placed ontop. The cover member 88 is held in place by three rods 89 which areinserted in apertures 90 formed in the front and rear side panels of theframe 86. The rods 89 pass through the openings 90 and then pass overthe top of the cover member 88, so that the air pressure caused by theair passing from the bottom to the top of the filter will not dislodgethe contents. As illustrated, the openings 90 are disposed verticallyalong the frame 86, so that the amount or thickness of filter media ineach filter basket can be varied to suit a particular application. Sincethe thickness of the filter media can be controlled, the pressure dropthrough this section of the gas scrubber can be adjusted to suitparticular applications. This feature also enables the gas scrubber ofthe invention to be readily modified in the field to suit changes inprocess or application. The filter baskets are preferably constructed ofmaterials which will not react with the scrubbing liquor in the sump 38or the chemical contaminants in the air being treated. For example, thebaskets may be fabricated of the stainless steel,

glass fiber or plastic materials which form the rest of the scrubberunit. As seen in FIGS. 2 and 3 of the drawings, the filter baskets 84and 85 are slidably supported on channels or brackets 91 which extendhorizontally along the housing side walls 31 and 32. Then the servicedoors 28 and 29 of the housing are opened, both filter baskets may beremove from the passageway 83 for servicing as required.

The filter basket 84 may be filled with a filter material or media, suchas beryl saddles, pall rings or tellerettes, for example. This filterstage provides an additional scrubbing and filtering action to removevery fine particles and contaminants in the air being treated. Two rowsof horizontally-disposed nozzles 92 are provided directly above filterbasket 84. One row of nozzles is provided along the length of ahorizontallydisposed pipe 93, while the second row of nozzles issimilarly disposed along the length of a pipe 94. Pipe 93 and the row ofnozzles 92 connected thereto are shown in detail in FIG. 7 of thedrawings. The same spray arrangement may also be employed for thepreviouslydescribed nozzles 76 and 80.

As seen in FIG. 1 of the drawings, the pipe 93 is connected by a teefitting 95, a coupling 96 and a second tee fitting 97 to one side of avalve 98. The other side of valve 98 is connected to a tee fitting 99which is coupled by means of pipes 61 and 62 to the output of pump 48,so that when valve 98 is opened, the liquid in the sump 38 is pumped toboth rows of the nozzles 92. The downward spray from the two rows ofnozzles 92 provides an additional scrubbing action and also washesdropped-out particulates from the filter media in the basket 84 into thesump section 42. The direction of the spray from nozzles 92 is oppositeto the direction of the air flow in passageway 83 to producecountercurrent mass transfer action for high efficiency scrubbing. Ifdesired, the liquid sprayed from nozzles 92 may be fresh water. To thisend, a pipe 100 having a valve 101 therein is connected to a fresh watersupply (not shown) and to the tee fitting 95, so that the fresh waterfrom the supply source is connected to both pipes 93 and 94 by the teefitting 95 and the pipe coupling 96. Accordingly, when valve 98 isclosed and valve 101 is opened, the liquid from the sump is preventedfrom entering the pipes 93 and 94 and the fresh water supply isconnected thereto.

After the air leaves filter basket 84 and the spray curtain from nozzles92, it passes through the second filter basket 85 which acts primarilyas a mist eliminator. The second filter basket may be filled with media,such as packing materials or wire mesh, for example, so that the finedroplets of moisture in the treated air will coalesce on the filtermedia and drop into the sump section 42 of the gas scrubber. If desiredto suit a particular application, all or part of the filter media forthe second basket 85 may consist of material such as activated charcoalwhich eliminates residual odors in the treated air. The thickness ordepth of filter material in the second basket 85 may also be controlledin the same manner as the material in basket 84, so that the pressuredrop in the filter section of the scrubber can be controlled to suit therequirements of a particular application. It is believed readilyapparent that both filter baskets are easily removed from the gasscrubber unit, so that the filter media may be cleaned or changed tosuit the requirements of a particular application. This feature alsopermits the gas scrubber of the invention to be readily modified in thefield when the requirements of a process are changed.

An alternative movable baffle arrangement for the gas scrubber of theinvention is shown in FIG. 8 of the drawings. In describing thisembodiment of the invention, reference characters with a prime notationwill be employed to describe parts which are the same as or similar tocorrespondingly numbered parts in the embodiment of FIGS. 1 through 7 ofthe drawings. As seen in FIG. 8, the throat portion 65 of the passagewayin the housing is again formed by a fixed baffle 57' and a movablebaffle 64. In this embodiment of the invention, the movable baffie 64'is formed with two substantially coplanar portions which are inclined atan acute angle to the plane of the fixed baffle 57. The inclined movablebaffle portions slope towards the fixed baffle 57 until they reach theapex 102, at which point the passageway 65' is narrowed down to a verysmall crosssectional area 103. This configuration provides a gradual andsmooth transition from the larger crosssectional area of the passagewayin the housing to the smaller cross-sectional area 103 of the throatportion 65. The smoother transition provided yields a lower overallpressure drop for this section of the gas scrubber and provides asomewhat greater scrubbing action at lower levels of energy consumption.The movable baffle 64 in this embodiment of the invention is supportedin exactly the same manner as the movable baffle 64 in the embodiment ofthe invention shown in FIGS. 1 through 7 of the drawings. In all otherrespects, this embodiment of the invention operates in exactly the samemanner as the previously-described embodiment.

Another alternative embodiment of the invention is shown in FIGS. 9 and10 of the drawings. In this embodiment, the variable Venturi or throatsection of the scrubber is formed by a fixed baffle and the surface ofthe liquid in the sump. As seen in FIG. 9, the air to be treated entersan inlet duct 201 and passes through an agglomeration spray from anozzle 202. After passing through the agglomeration spray, the air isdeflected downwardly through a passage 202 formed by a fixed baffle 204and the rear wall 205 of the housing. The housing is formed insubstantially the same manner as the housing shown in FIGS. 1 through 7of the drawings and is provided with a liquid-filled sump area 206.Although not illustrated, it will be understood that a twostage sumpportion may be employed in place of the single-stage sump shown in FIG.9 if desired. The level of the surface 207 of the liquid in the sump maybe controlled by an adjustable surface drain arrangement 208 and by afloat valve (not shown) in the same manner as the previously-describedembodiments of the inven tion. The fixed baffle 204 is provided, at thelower end thereof, with a c-shaped" portion 209 which extends from sidewall to side wall of the housing. A horizontally-extending pipe 210having a row of nozzles 21] spaced along the length thereof is mountedon the lower edge or apex 212 of the baffle 209, so that a substantiallyvertical curtain of liquid spray is formed across the opening 213 whichis formed by the apex 212 of the baffle and the surface 207 of theliquid in the sump.

Accordingly, as the untreated air is drawn through the passageway 203 bythe action of the blower (not shown), the area of the passageway isgradually narrowed down until it reaches the relatively smallcrosssectional area or throat 213 which is formed by the curved portion209 of the baffle and the surface 207 of the liquid in the sump. At thispoint, the smaller crosssectional area causes the velocity of the air tobe substantially increased to that the Reynolds Number and turbulenceare increased to provide optimum atomization of the spray from thenozzles 211. As the atomization of liquid particles is increased by thehigh velocity of the air passing through the throat, the scrubbingefficience is increased together with the pressure drop through theunit. The high velocity of the air stream through the throat 213 tendsto atomize both the liquid from the spray nozzles 211 and the liquidwhich is sheared off from the surface of the sump. In this arrangement,the cross-sectional area of the throat 213 may be easily controlled bymeans of the adjustable surface drain 208 or the float valve (notshown). When the gas scrubber is employed in a process having arelatively low rate of air flow, the water level in the sump may beraised to produce the high velocity needed for good scrubbing action.Similarly, when the scrubber is used in an application having arelatively high rate of air flow, the water level may be lowered toproduce the same optimum velocity.

After the scrubbed air leaves the throat portion 213 of the scrubber, itpasses through a passageway 214 which is connected to an outlet duct 215mounted on the top 216 of the scrubber housing. The filter section inpassageway 214 consists of two removable filter baskets 217 and 218which may be constructed in the same manner as the filter basketsemployed in the embodiment of FIGS. 1 through 7 of the drawings. Bothfilter baskets are slidably mounted on horizontally extending brackets219 which are secured to the side walls of the scrubber housing. Sincethe baskets are mounted side by side in the output passageway 214, theymay each be filled with the same filter media and may, if desired, bereplaced by a single large basket. The undersides of the baskets 217 and218 are irrigated by the liquid spray from four horizontally-extendingrows of nozzles 220 which are connected to pipes 221 and 222. The pipe221 and nozzles 220 mounted thereon are shown in detail in FIG. 10 ofthe drawings wherein it is seen that two rows of the nozzles 220 aresupplied by a single one of the pipes 221 and 222. The pipes 221 and 222may be connected to the water or liquor in the sump 206 by piping (notshown) or may be connected directly to fresh water, if desired. Thespray produced by the nozzles 220 provides a further scrubbing action toremove fine particles from the air entering the output passageway 214and also serves to irrigate the undersides of the filter baskets 217 and218 to remove particulates and other matter which accumulates in thefilter section. A row of apertures or holes 223 is provided across thelength of the apex portion 212 of the baffle 204 so that water or otherliquid falling down into the depression formed by the curved lower endof the baffle may pass through the apertures and back into the sump 206of the unit. The liquid dripping through the holes 223 also forms acurtain of liquid drops across the throat area 213 and is atomized bythe high velocity air passing therethrough to further increase thescrubbing efficiency of the unit. This embodiment of the invention may,if desired, also be provided with a two stage gas filter section in theoutput passageway 214 and with additional spray means for greaterscrubbing action. Similarly, inertial separation sections may also beadded for further operating efficiency.

It is believed apparent that many changes could be made in theconstruction and described uses of the foregoing gas scrubber and manyseemingly different embodiments of the invention could be constructedwithout departing from the scope thereof. For example, the configurationof the various passageways and sections in the gas scrubber could bechanged in design and still provide the basic scrubbing and filteringactions required. Accordingly, it is intended that all matter containedin the above description or shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Gas scrubbing apparatus comprising a housing having a gas inlet and agas outlet;

baffle means in said housing forming a passageway therethroughconnecting the gas inlet and the gas outlet, said baffle meanscomprising fixed baffle means connected to said housing and at least onemovable baffle spaced from said fixed baffle which defines with saidfixed baffle means an adjustable throat portion of reducedcross-sectional area in said passageway; means for adjusting saidmovable baffle;

spray means disposed in said throat portion in a plane substantiallyperpendicular to the direction of gas flow for producing a liquid sprayacross said throat portion transversing the direction of gas flow;

a liquid-filled sump portion in said housing; and

sump filter screen means dividing said sump portion into at lease afirst sump section disposed beneath said gas inlet and said throatportion and a second sump section coupled to said spray means forsupplying spray liquid thereto,

whereby gas passing through said throat portion from the gas inlet tothe gas outlet is increased in velocity and turbulence and scrubbed bythe liquid spray and said sump filter screen means is operable toprevent particulates and other contaminants falling into said first sumpsection from entering said second sump section, to thereby preventclogging of said spray means.

2. Gas scrubbing apparatus as claimed in claim 1 further comprising atleast one gas filter basket disposed in said passageway adjacent saidgas outlet for filtering the gas passing through said passageway,

support means in said housing for slidably supporting said filterbasket, and

service door means in said housing adjacent said support means to permitremoval of said filter basket from said housing.

3. Gas scrubbing apparatus as claimed in claim 2 wherein said gas filterbasket comprises a hollow frame having one end thereof closed by a gaspermeable end member,

a cover member of gas permeable material remov ably disposed in theother end of said frame,

gas filtering material disposed within said frame between said cover andend members, and

means for securing said cover member to said frame at predetermineddistances from said end member to permit adjustment of the thickness ofthe filter material in said basket.

4. Gas scrubbing apparatus comrising a housing having a gas inletadjacent one end thereof,

a gas outlet adjacent the other end thereof, and a liquid-filled sumpportion at the bottom thereof; baffle means in the interior of saidhousing cooperating with the surface of the liquid in said sump portionto form a tortuous passageway connecting the gas inlet with the gasoutlet, said baffle means comprising fixed baffle means connected tosaid housing and at least one movable baffle spaced from said fixedbaffle which defines with said fixed baffle means an adjustable throatportion of reduced cross-sectional area in said passageway;

means for adjusting said moveable baffle;

sump filter screen means dividing said sump portion into a first sumpsection disposed beneath said gas inlet and said throat portion and asecond sump section disposed beneath said gas outlet, said sump filterscreen means being operable to prevent particulates and othercontaminants falling into said first sump section from entering saidsecond sump section;

spray means mounted on said baffle means in said throat portion in aplane substantially perpendicular to the direction of gas flow andcoupled to said second sump section for producing a liquid spray acrosssaid throat portion transversing the direc tion of gas flow, whereby gaspassing through said throat portion is increased in velocity andturbulence and scrubbed by the liquid spray; and

at least one gas filter basket removably disposed in said passagewayadjacent said gas outlet for filtering the gas passing therethrough.

5. Gas scrubbing apparatus as claimed in claim 4 wherein said fixedbaffle means comprises a fixed baffle adjacent said gas inlet fordirecting the gas from said inlet toward the surface of the liquid insaid first sump section to provide for inertial separation of theparticulates and other contaminants in said gas.

6. Gas scrubbing apparatus as claimed in claim 5 wherein wherein each ofsaid movable and fixed baffles is substantially coplanar and the planeof the movable baffle is substantially parallel to the plane of thefixed baffle.

8. Gas scrubbing apparatus as claimed in claim 6 wherein said fixedbaffle is substantially coplanar, and

said movable baffle has two portions disposed above the surface of theliquid in said sump portion opposite said fixed baffle, each of saidmovable baffle portions being substantially coplanar and inclined at anacute angle with the plane of said fixed baffle,

so that the cross-sectional area of the throat portion formed by saidbaffles decreases to a minimum at the apex of the two inclined portionsof said movable baffle to provide a smooth transition from the largercross-sectional area of the passageway to the smaller cross-sectionalarea of said throat portion.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3.856.487Dated December 24 1974 Inve t r( Manuel Pere 2 It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 4, line 27, after "34" insert is connected to the top 23 and thetwo side panels 31 and 32-. Column 5 line 45, after "60" insert Column10, line 42, delete "202" and insert therefor -203--.

Signed and sealed this 15th day of April 1975.,

1 I. i, .Ltt st C lL- .I;3II.="-. BI S-'2" ZLL 'ZZ. C. 1;..3 COTI'iioner 0' Patents l-lttest'in; Qfificer Trademark-".5

FORM po'wso (10459) USCOMM-DC 60376-P69 ".5. GOVERNMENT PRINTING OFFICEI IQQ 0-355-334,

1. Gas scrubbing apparatus comprising a housing having a gas inlet and agas outlet; baffle means in said housing forming a passagewaytherethrough connecting the gas inlet and the gas outlet, said bafflemeans comprising fixed baffle means connected to said housing and atleast one movable baffle spaced from said fixed baffle which defineswith said fixed baffle means an adjustable throat portion of reducedcross-sectional area in said passageway; means for adjusting saidmovable baffle; spray means disposed in said throat portion in a planesubstantially perpendicular to the direction of gas flow for producing aliquid spray across said throat portion transversing the direction ofgas flow; a liquid-filled sump portion in said housing; and sump filterscreen means dividing said sump portion into at lease a first sumpsection disposed beneath said gas inlet and said throat portion and asecond sump section coupled to said spray means for supplying sprayliquid thereto, whereby gas passing through said throat portion from thegas inlet to the gas outlet is increased in velocity and turbulence andscrubbed by the liquid spray and said sump filter screen means isoperable to prevent particulates and other contaminants falling intosaid first sump section from entering said second sump section, tothereby prevent clogging of said spray means.
 2. Gas scrubbing apparatusas claimed in claim 1 further comprising at least one gas filter basketdisposed in said passageway adjacent said gas outlet for filtering thegas passing through said passageway, support means in said housing forslidably supporting said filter basket, and service door means in saidhousing adjacent said support means to permit removal of said filterbasket from said housing.
 3. Gas scrubbing apparatus as claimed in claim2 wherein said gas filter basket comprises a hollow frame having one endthereof closed by a gas permeable end member, a cover member of gaspermeable material removably disposed in the other end of said frame,gas filtering material disposed within said frame between said cover andend members, and means for securing said cover member to said frame atpredetermined distances from said end member to permit adjustment of thethickness of the filter material in said basket.
 4. Gas scrubbingapparatus comrising a housing having a gas inlet adjacent one endthereof, a gas outlet adjacent the other end thereof, and aliquid-filled sump portion at the bottom thereof; baffle means in theinterior of said housing cooperating with the surface of the liquid insaid sump portion to form a tortuous passageway connecting the gas inletwith the gas outlet, said baffle means comprising fixed baffle meansconnected to said housing and at least one movable baffle spaced fromsaid fixed baffle which defines with said fixed baffle means anadjustable throat portion of reduced crOss-sectional area in saidpassageway; means for adjusting said moveable baffle; sump filter screenmeans dividing said sump portion into a first sump section disposedbeneath said gas inlet and said throat portion and a second sump sectiondisposed beneath said gas outlet, said sump filter screen means beingoperable to prevent particulates and other contaminants falling intosaid first sump section from entering said second sump section; spraymeans mounted on said baffle means in said throat portion in a planesubstantially perpendicular to the direction of gas flow and coupled tosaid second sump section for producing a liquid spray across said throatportion transversing the direction of gas flow, whereby gas passingthrough said throat portion is increased in velocity and turbulence andscrubbed by the liquid spray; and at least one gas filter basketremovably disposed in said passageway adjacent said gas outlet forfiltering the gas passing therethrough.
 5. Gas scrubbing apparatus asclaimed in claim 4 wherein said fixed baffle means comprises a fixedbaffle adjacent said gas inlet for directing the gas from said inlettoward the surface of the liquid in said first sump section to providefor inertial separation of the particulates and other contaminants insaid gas.
 6. Gas scrubbing apparatus as claimed in claim 5 wherein saidmovable baffle is disposed adjacent said fixed baffle and has the lowerend thereof extending below the surface of the liquid in said first sumpsection, the space between said fixed and movable baffles forming thethroat portion of said passageway, said movable baffle being movable ina direction substantially perpendicular to the direction of gas flowbetween said baffles.
 7. Gas scrubbing apparatus as claimed in claim 6wherein each of said movable and fixed baffles is substantially coplanarand the plane of the movable baffle is substantially parallel to theplane of the fixed baffle.
 8. Gas scrubbing apparatus as claimed inclaim 6 wherein said fixed baffle is substantially coplanar, and saidmovable baffle has two portions disposed above the surface of the liquidin said sump portion opposite said fixed baffle, each of said movablebaffle portions being substantially coplanar and inclined at an acuteangle with the plane of said fixed baffle, so that the cross-sectionalarea of the throat portion formed by said baffles decreases to a minimumat the apex of the two inclined portions of said movable baffle toprovide a smooth transition from the larger cross-sectional area of thepassageway to the smaller cross-sectional area of said throat portion.